This invention relates to a perforated tape reader, wherein data is recorded in a plurality of longitudinal channels, by means of the presence or absence of perforations.
According to this invention, the device consists of drive means for moving said perforated tape in respect to a plurality of detecting elements associated with said perforated tape, a plurality of rocker arms pivoting on a fixed shaft, said detecting elements mounted on one of its ends and provided with a fork having an upper and a lower arm at the other end, a plurality of conducting elements selectively moved from a first to a second position of said rocker arms and designed to close electric circuits, a plurality of fixed contacts, located in correspondance with said plurality of conducting elements, elastic means associating with said rocker arms to keep said detecting elements in contact with said perforated tape.
In the already known device described in U.S. Pat. No. 3,733,467, the elements detecting perforations on perforated tape consist of star wheels pivotly mounted on one end of a plurality of lever arms, pivoting on a fixed pin.
Each lever arm is biased against the tape by means of a leaf spring. The leaf spring is the means used for closing the electric circuit for tape reading. In fact, when the point of the star wheel penetrates a perforation in the tape, the corresponding lever arm rotates in a counter-clockwise sense. The other end of the lever arm engages an adjustable set-screw 104 in FIG. 2, owing to the action of spring 100, which in its turn touches an electric contact 112 having an adjustable set-screw to close the electric reading circuit.
This device is very complex as it requires assembling as many springs as there are lever arms, that is as many perforations, plus any eventually other lever arms needed.
Furthermore, an extremely delicate and accurate initial adjustment is required as the set-screws and contact-screws have to be adjusted one at a time when they are assembled.
During operation, these screws may accidentally loosen thus altering data reading.
Another major inconvenience of this reading device is that the springs are directly connected to the respective lever arms, so that each movement of the latter is directly transmitted to the springs and thus any eventual rebound of the wheels against the perforated tape affects the springs, thus causing irregular contacts and consequently abnormal opening and closing of the electric reading circuit.
These anomalies cause irreparable incorrect reading of data contained in the tape.